"Al Unser Sr. was one of the smartest drivers I've ever raced against. And I often said, I wish I could've had some of his patience. I know it would have worked for me many times,"said Mario Andretti on ESPN Classic's SportsCentury series.

He is the most accomplished among what has evolved into America's leading auto-racing family. Al Unser Sr., one of only three four-time winners of the Indy 500, is the younger brother of three-time Indy winner Bobby and the father of two-time champ Al Jr.

An intelligent driver who rarely made a mistake, Unser possessed a raging fire. While he didn't show this emotion outwardly, he had this burning desire to be the best.

"He's one of the top five racers who has ever lived," said Andretti. "Nobody had race savvy like Al Unser in his prime."

Born on May 29, 1939, in Albuquerque, Al, the youngest of four sons, entered the world with racing in his blood. His father Jerry and two uncles, Louis and Joe, were also drivers. Beginning in 1926 they competed in the Pikes Peak International Hill Climb, an annual road race held in Colorado, but never made it to Indy.

Joe Unser became the first member of the Unser clan to lose his life to the sport, killed while test-driving a FWD Coleman Special on the Denver highway in 1929.

Al's oldest brother Jerry became the first Unser to drive in the Indy 500, finishing 31st in the 1958 race. However, tragedy struck the next year when he was killed from injuries sustained in a fiery crash during a practice run.

Middle brother Bobby drove in his first Indy 500 in 1963. In 1991, Al Jr. became the first second-generation Indy 500 champion. Also on the Indy roster are Jerry's son, Johnny, and Bobby's son, Robby.

Can you spell D-Y-N-A-S-T-Y?

The Unser family's achievements are nonpareil in its sport: Six Unsers have started the Indy 500, and since 1968, the nine victories by Al, Bobby and Al Jr. have accounted for more than 25 percent of the race's winners. They are auto racing's version of the Yankees.

In 1957, at 18, Al Unser Sr. began his racing career, initially competing primarily in modified roadsters, sprint cars and midgets. His first Indy 500 start came in 1965, and he finished ninth.

In 1970, two years after Bobby won his first Indy 500, Al Sr. entered victory lane, making the Unsers the only brothers to win at the Brickyard. After capturing the pole position in his Johnny Lightning Special, he led for all but 10 of the 200 laps and averaged 155.749 miles per hour.

His legendary prowess for quick pit stops helped him gain the victory. On his second stop, Unser cleared the pits in only 22 seconds. Foyt, who trailed by just five seconds, pulled into the pit but confusion among the crew forced him to return to the track and re-fuel the next time around. That error cost him 32 seconds.

For Al Sr., 1970 turned into one of the outstanding racing seasons. He won a record 10 times on oval, road and dirt tracks to capture the United States Auto Club national championship.

"I don't think anybody ever had a year like that in USAC," he says. "I mean, everything went right that year. Everything. The car was right. The mechanics. I was right. You find that very seldom. I was almost unbeatable."

The following year, starting from the fifth position, he averaged 157.735 and won the Indy 500 again, joining Wilbur Shaw (1939-40), Mauri Rose (1947-48) and Bill Vukovich Sr. (1953-54) as back-to-back winners. "The big difference for me was the first time I won, I lost all sense of direction," said Unser. "I couldn't find victory lane afterward. The second time, I knew just where to go."

The race was crash-filled, and his brother Bobby was involved in one of the mishaps. Mike Mosely hit the wall going into turn four, losing a tire in the process. Mosely's car erupted in flames. The speeding projectile that had been Mosely's tire struck Bobby's car, which had been following Mosely into the turn. Bobby's car spun and also hit the wall.

Mosely needed to be extricated, and was hospitalized with a broken leg and severe burns. Bobby came out of the incident unscathed -- except for a "severe headache" -- but Al, who had taken the lead for good on lap 118, wondered whether his brother had escaped the carnage.

"I knew Bobby was in that mess, but on the next lap I saw him standing there, waving at me," he said. "It was a comfort."

Unser's bid to become the first "three-peat" Indy 500 champion missed when he finished second to Mark Donohue in 1972.

In 1978, Al Sr. was considered a long shot, though he started from the fifth position in his FNCTC Chaparral Lola. He took the lead on lap 75 and by the race's halfway mark he had opened up a 23-second edge over Danny Ongais.

However, with less than one-third of the race remaining, the lead had dwindled to 5.8 seconds. But when Ongais blew an engine at the 137.5-mile mark, Unser's drive became easier. Averaging 161.363 mph, he held off pole-sitter Tom Sneva, Rick Mears and Gordon Johncock to capture his third Indy 500 crown.

With his 39 career victories, Unser ranked third all-time for CART wins heading into 2001.

In 1983, he became the first driver to race against his son at Indy. That year, he captured the CART championship series, a feat he repeated in 1985.

By 1987, though, it appeared that age might have passed him by. Almost 48, he left Albuquerque not knowing if he would even have a ride in the Indy 500. Unser, who had performed admirably for Roger Penske's team for four years, had been unceremoniously dropped by Penske, who went with Mears, Ongais and Danny Sullivan.

However, when Ongais crashed into the wall during the first week of practice at Indy and was unable to drive, Penske turned to his legendary veteran to drive a backup car, a 1986 March-Cosworth.

When the familiar "Gentlemen, start your engines!" rang through the P.A. system at the Brickyard, Unser was in the 20th position. But working his way steadily through the field, he took the lead on the 183rd lap. Averaging 162.175 mph, Unser held off a charging Roberto Guerrero by 4.5 seconds to win his fourth Indy 500 just five days before his 48th birthday. In doing so he tied Foyt as the winningest Indy 500 driver (Mears would join them as a four-time winner in 1991) and broke brother Bobby's record as the oldest Indy winner. And in a used car, no less!

"Al just knows how to win a race," said Penske. "He stays out of trouble. Just look at his career. You don't win this thing four times because you don't know what's going on."

Nearing 55, Unser waved the checkered flag on his illustrious career on May 17, 1994, one day after struggling to qualify for his 28th Indy 500.

"I always said if the day came when I wasn't producing the right way, if I wasn't happy, I'd get out," he said. "The time has come. A driver has to produce 100 percent. You can't just come in and strap one of these cars on and expect to give answers to the team that they need. I finally realized that it just wasn't there, and I wasn't producing like I should."